Titanium dioxide nano-material is a hotspot in the research of material science over the past three decades. Titanium dioxide nanocrystal is an oxide which has been most intensively studied, because they are widely applied in photocatalysis, sensors, solar cell, mesoporous film and the like. In addition, the titanium dioxide nanomaterial due to its feature in the nano-scale tends to complex with an organic material having a high or low molecular weight to manufacture a device such as a solar cell by a method such as spin coating and the like. The titanium dioxide nanocrystals exhibit a very attractive prospect in photovoltaic conversion. Therefore, the methods for preparing titanium dioxide nanocrystals have been intensively studied.
Heretofore, various methods have been used to prepare titanium dioxide nanocrystals, including hydrothermal method (Chem. Mater. 1995, 7, 663; Chem. Mater. 1999, 11, 2770; Chem. Mater. 2002, 14, 1974), and sol-gel method (Science, 1994, 266, 1961; Langmuir, 1996, 12, 1411; Adv. Mater. 2002, 14, 1216). In general, the titanium dioxide nanocrystals prepared by above two methods have a larger particle diameter, and those nanocrystals with a diameter less than 10 nm can hardly be produced. The resulting titanium dioxide nanocrystals can not be dispersed uniformly in an organic solvent and exhibit a broad size distribution.